Theoretical Accuracy of a Meteorological Rocketsonde Thermistor

Abstract

The ability of the bead thermistor currently used in meteorological sounding rockets to measure the ambient kinetic temperature of the environment is examined theoretically. A non-steady state heat transfer environment including forced convection, infrared and solar radiation, compressional heating, lead wire conduction and internal heating is considered, along with normal variations to be expected in this environment. The average temperature measurement error is found to range from less than 5C at heights below 50 km to 33.5C at 65 km. Correction for this error should yield ambient temperature values to within ±2 per cent up to 60 km with the correction accuracy decreasing to ±3.8 per cent at 65 km. The correction accuracy deteriorates rapidly above 65 km suggesting that either a different type sensing element or a different sounding technique will be necessary for temperature measurement above this level. Although the theoretical temperature error was computed on the basis of mean model atmospheric temperature distributions, it is shown that the results may be applied to individual soundings as long as abrupt changes in algebraic sign of the environmental lapse rate do not occur.